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Structural Aspects of the β ‐Polymorph of ( E )‐4‐Formylcinnamic Acid: Structure Determination Directly from Powder Diffraction Data and Elucidation of Structural Disorder from Solid‐State NMR
Author(s) -
Meejoo Siwaporn,
Kariuki Benson M.,
Kitchin Simon J.,
Cheung Eugene Y.,
AlbesaJové David,
Harris Kenneth D. M.
Publication year - 2003
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200390130
Subject(s) - chemistry , rietveld refinement , powder diffraction , crystal structure , crystallography , cinnamic acid , diffraction , solid state , solid state nuclear magnetic resonance , x ray crystallography , resolution (logic) , organic chemistry , nuclear magnetic resonance , optics , physics , artificial intelligence , computer science
Abstract Among the derivatives of ( E )‐cinnamic acid for which the solid‐state photochemical properties have been studied, ( E )‐4‐formylcinnamic acid ( 1 ) has already received much attention. Given the inability to prepare single crystals of the β ‐polymorph of 1 that are of suitable size and quality for structural characterization by single‐crystal X‐ray diffraction, the structure of this material was determined directly from powder X‐ray‐diffraction data by means of the genetic‐algorithm technique for structure solution, followed by Rietveld refinement. High‐resolution solid‐state 13 CNMR was also applied to elucidate details of structural disorder concerning the orientation of the formyl group, and provided independent support for the disorder model established form the Rietveld refinement. The reported structure establishes that the β ‐phase of 1 is not structurally anomalous among photoreactive ( E )‐cinnamic acid crystals, and finally resolves a long‐standing controversy concerning the structural properties of this material.